Generally in the case of thermoplastic synthetic fibers such as polyester, nylon, polypropylene, etc., a lubricant for treating fibers is attached to unstretched yarns obtained by melt-spinning, followed by stretching to 3 to 4 times the original length and heat-set for fixing the properties. The resulting stretched yarns are further passed through advanced processing steps such as bulky processing, twisting, warping, sizing, knitting, weaving, etc. to give fiber products, and in such production and processing steps, yarns are industrially treated very often at considerably high speed for improving their productivity; thus various obstacles accompanying the treatment such as attrition of guides, travellers, knitting needles, etc. contacting with filaments, various electric obstacles such as fiber-breakage due to approach of filaments at the time of warping, contact thereof with the second heater and twining round nip rolls in a false twist processing machine, etc. have become a more and more serious problem. Thus a fiber-treating lubricant capable of diminishing such obstacles has been earnestly required.
As an antistatic agent component for fiber-treating lubricants used in the production and processing steps of synthetic fibers, various kinds of anionic surfactants, cationic surfactants, amphoteric surfactants, etc. have so far been used in admixture, but those which satisfy all of problems of antistatic property, lubricating property to metals, the so-called lubricating property and collecting property such as high speed unwinding from pirn, cheese, etc., resistance to attrition of metals, and the like properties, have not yet been developed. Further, when lubricants using such ionic surfactants are made up into an aqueous emulsion to be applied to fibers, the resulting foam is too large, resulting in adhesion unevenness of lubricants; hence development of an antistatic agent having little foaming property has been particularly awaited.
Further, surfactants as the above-mentioned component being currently most often used for the antistatic purpose are anionic surfactants, but those having properties which fully satisfy the above-mentioned purpose under a severe condition of an atmosphere of extremely low humidity (RH: 30% or lower), have not yet been found. For example, as anionic surfactants used so far, there are alkali metal salts or alkanolamine salts of long-chain alkyl phosphates, which, however, have drawbacks of being liable to wear frictional bodies as described above and lowering antistatic property at the time of high temperature heat treatment or at the time of low humidity. Further, surfactants of alkylsulfate salt or alkylsulfonate salt type exhibit superior antistatic property under an atmosphere of high humidity or medium humidity, but they are not yet fully satisfactory under an atmosphere of extremely low humidity (RH: 30% or lower), and if the amount thereof added is increased in order to supplement the insufficiency of the property, their lubricating property becomes notably inferior, and further, when they are dissolved in water, their emulsion causes a notable foaming due to reduction in the surface tension.
Furthermore, aliphatic carboxylic type anionic surfactants represented by alkali metal salts of oleic acid or ricinoleic acid exhibit desirable properties in the aspect of antistatic property as compared with the above-mentioned other anionic surfactants, but their antistatic property under an extremely low humidity and their properties in the case where the amount thereof added is increased, have similar drawbacks to those of the above-mentioned alkylsulfate salt and alkylsulfonate salt type surfactants.
Further, in order to improve sizing property, generally the proportion of anionic surfactants in the lubricant may be increased, but this case also exhibits similar drawbacks to the above-mentioned. Further, in the case where polymers having a number of carboxyl groups in the molecule such as copolymers of maleic anhydride with a water-soluble vinyl monomer or alkali metal salts or ammonium salts of polyacrylic acid, etc. are used as a fiber-treating agent, they exhibit an excellent effectiveness of improving collecting property, but, on the other hand, friction of fibers to metals at high speed is very great, and also such carboxylic acid salts of polymers have almost no antistatic effectiveness.